The invention is directed toward self-propelled appliances. The invention will be described in reference to a self-propelled vacuum cleaner. However, it should be understood that the invention can be applied in other self-propelled appliances. For example, the invention can be applied in self-propelled shampooers, sweepers, sanders, waxers, and lawn mowers.
Self-propelled appliances, such as, for example, self-propelled vacuum cleaners, include gearing mechanisms to provide motor power to drive wheels. For example, many self-propelled vacuum cleaners include one and/or a second motor to provide working air flow and propulsion to the drive wheels. Self-propelled vacuum cleaners often require clutches in order to provide forward and reverse gearing. Furthermore, some such vacuum cleaners include a limit switch/sensor for determining a handle position or other parameter that can be used to control motor operation for either the wheel drive or a revolving cleaning brush. For instance, movement of a handle to an upright storage position has been used as a basis to disable the brush movement.
In any self-propelled appliance device, there is always a need to provide improved better control of applied power to the drive mechanisms. The ability to interrupt power to the drive mechanism at a time when the user clearly does not intend to operate the appliance in a self-propelled state is important. A control system to effect this intent is of concern to a user not only for convenience, but also for safety.
Of particular safety concern is that at any time during normal operation of the appliance, if any of the circuitry were to fail, the motor and drive system could be locked into a fully forward or reverse state and cause injury to the user.